Flexibility in thermal physiology and behaviour allows body mass maintenance in hibernating hazel dormice

Studying animals under natural or semi-natural conditions is essential to better understand the implications of a warming climate on species survival. Here, we provide evidence effects increasing winter ambient temperature (Ta) thermal physiology, feeding behaviour and body mass (BM) small mammalian hibernator, hazel dormouse Muscardinus avellanarius. We collected skin temperature, metabolic rate (MR) BM data from captive, hibernating dormice exposed two winters differing intensity in outdoor aviaries. Additionally, obtained one free-ranging individual during hibernation period. Statistical modelling showed that Ta time since start both had significant non-linear probability arousal torpor. During warmer (Ta<0°C 26 days), foraging resulted higher BMs for some individuals, despite more frequent arousals, than colder 86 days). As expected, effect MR torpor, with lowest energy expenditure at intermediate Ta, normothermic was minimal when warmer. The negative increased frequency counteracted by positive BM. Conforming accumulating high flexibility physiological responses many mammals, found thermoregulatory behavioural were flexible previously observed this temperate, fat-storing species. ability respond prevailing environmental might help M. avellanarius cope predicted ongoing global warming.